Keezer temp too low with Johnson A419

So I plugged in my keezer for the first time yesterday evening. I have the Johnson A419 to control the temp inside, and the probe is placed inside a jar full of chopped up rice to keep temp more consistent and less prone to simple air temp fluctuations. The controller is set to 43F +/- 2F, and I set the freezer to it's coldest setting. I checked it last night and it was down to 41F, but the compressor had just finished being on. I woke up this morning to find the keezer at 37F! The settings all seem fine and probe is still firmly nestled in the jar with the chopped up rice, so I'm at a loss as to how the temp has dropped so precipitously.

The only thing I can guess is that the two kegs in there absorbed too much cold and are keeping the temp low OR that the freezer being on it's coldest setting causes too much cold to be created before the probe adjusts and realises the over cooling. The probe is on the opposite end of the keezer from the two kegs at the moment, but I think it's too much of a difference to really make sense.

I too have been running into problems with my (new) Johnson A419. I wonder if there is a bad batch of these controllers out there because mine certainly does not seem to be all that accurate. I have programmed it to 36' +/- 1' for lagering and the temps are all over the map but always on the very cold side. Often I find it at 32'-33' and it is fairly rare that it will hit the target temp. I find myself programming it for around 39' because I know it will drop down to around 35 when all is said and done. Curiously, my Johnson analog temp controller is dead on consistent at +/- 2'. Montanaandy

Do yourself a favor and take the bulb out of the ice and tape it to the side of the keg. Trust me i've done every way there is to do, this is the simplest and most effective.

Why would you care what the temp of a glass of ice is?

wildwest450 said:

Do yourself a favor and take the bulb out of the ice and tape it to the side of the keg. Trust me i've done every way there is to do, this is the simplest and most effective.

Why would you care what the temp of a glass of ice is?

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Not ice, Rice. The theory is that the mass of the rice will be a more consistent temperature that doesn't fluctuate as much as the air temp will. Very similar to taping the probe to the side of the keg, without always having to switch the probe around. All of our temp probes when I worked at the lab were immersed in some sort of medium, either a gel or sand. I had neither (and didn't know how the temp probe would be affected by liquids anyway), so I threw some rice in a blender and ground it up and stuck the probe in a jar full of that. As I said, it could just be that the jar takes a while to get to the right temp, as the unit has just been turned on and is fighting to cool the 10 gals of beer inside, so by the time the mass of the rice in the jar has cooled, it's gone too far. If that's true, this shouldn't happen long term, but I was wondering if anyone else had a similar experience and deal with a potential problem before it got out of hand.

Montanaandy, what do you put your probe in?

wildwest450 said:

Do yourself a favor and take the bulb out of the ice and tape it to the side of the keg. Trust me i've done every way there is to do, this is the simplest and most effective.

Why would you care what the temp of a glass of ice is?

Click to expand...

I think he is using rice not ice..


mine was a little jumpy when I first set it up but its been pretty stable since. remember the sides get well below freezing when the unit is on I get some ice on the sidewall sometimes. So its going to drop a few degrees after it turns off.

just wanted to add I keep the probe in the air . My reasoning is when you put 5 gallons of beer in and its say 55° it takes a while for it to stabilize to the temps. Even with a jar filled with rice water or whatever it will take longer for the temp to reach your set point at which time the ambient may be well below freezing. My setup runs maybe 2-3 minutes every 4 or 5 hours.

I was under the understanding that there was a liquid inside the probe and that helped it keep stable readings and these were designed not to need a liquid or rice chamber.

I've had mine hanging in the air a couple inches from the freezer back wall, a few inches above the floor, and set at 37F for about two weeks now. I have a thermometer in a glass of water that has been reading 38F every time I check it.

it's going to be jumpy when you first turn it on, it has to stabilize. it will move around a tad once you start swapping mass as well.

i don't think there is liquid inside the probe.

springer said:

. . . just wanted to add I keep the probe in the air.

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Me too - here's a pic of mine. It hangs about 3" from the back wall.

Adding the fan to circulate the air was the last piece to getting consistent temps. I've got two setup like this and after cycling off both temps on the controllers will drop below their set point. But when testing/measuring the temps inside they are steady.

Hope this helps.

So you guys have pretty much confirmed my suspicions then that it's just the mass of the ground rice taking longer to get down to temp, so the freezer keeps running. I'm going to keep the probe in the jar for now, when the freezer does stabilise, it'll help prevent the compressor from kicking on as often. If the small amount of rice I have in the jar isn't getting up above the temp I want, then the multiple gallons of beer in the kegs certainly isn't.

As for a fan, I'm planning on adding one soon. I think I'm going to use the power that the lid light has to make it run whenever the compressor is going (don't feel the need to circulate the air full time, seems like a waste of power).

The rice could be the problem. I do not know what the thermodynamics of rice is, but if it is acting as an insulator that could be the problem as the probe surrounded my an insulating medium is taking longer to get to ambient temperature than the liquid in the kegs. I keep my probe in a small glass jar filled with liquid.

"Montanaandy, what do you put your probe in?"

Ah, well... I just let it hang loose from the back top of the keezer down near the back wall (I knew that no matter how I answered this question I was going to get burned

With the analog model I have it sitting flat on the keezer bump out.

I have mine in open air also. In a chest freezer, it's less of an issue because even when you open the lid, the cold air doesn't just spill out. Also, there's already enough thermal mass in the metal of the probe that a short temporary drop in air temp is not going to kick the compressor on. Besides, you have the ASD set to something like 5 minutes right?

Zen_Brew said:

The rice could be the problem. I do not know what the thermodynamics of rice is, but if it is acting as an insulator that could be the problem as the probe surrounded my an insulating medium is taking longer to get to ambient temperature than the liquid in the kegs. I keep my probe in a small glass jar filled with liquid.

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I was going to do that, but I wasn't sure how the probe would do in liquid.

Bobby_M said:

I have mine in open air also. In a chest freezer, it's less of an issue because even when you open the lid, the cold air doesn't just spill out. Also, there's already enough thermal mass in the metal of the probe that a short temporary drop in air temp is not going to kick the compressor on. Besides, you have the ASD set to something like 5 minutes right?

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I know I'd likely be fine, but it's a left-over habit from my lab days... Just doesn't seem right to have the probe not in something

Ice or rice , i'm still right.

Gremlyn1 said:

I was going to do that, but I wasn't sure how the probe would do in liquid.

I know I'd likely be fine, but it's a left-over habit from my lab days... Just doesn't seem right to have the probe not in something

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Well you have to take a look at how they have sealed the area where the wire goes into the probe body. I can't say for certain as I have a Ranco controller. Probably a good idea to stay away from solvents as your liquid as well. I just took a Trader Joes Spice jar, poked a hole in the top of the lid, and filled it up with a water/glycerine mixture. I remember we used to use glycerine as the temp medium in an old Thermoelectric Icepoint reference at a cal lab I worked at years ago.

I suspect ambient air would work as well, particularly if you are circulating the air with a fan inside the unit. I understand the habit of putting the temp sensor into something. Being a metrologist I have the same propensity to tweak stuff.

I just have it in open air and it's been fine. Also, remember that the temps will stabilize better if it's full of kegs, bottles and whatnot.

the A99B sensor should be waterproof.

I leave mine in open air. note, you can average these just like you can average any resistance circuit, if you are so inclined.

"Also, remember that the temps will stabilize better if it's full of kegs, bottles and whatnot."

Yeah, that may be the problem. I have it in a smaller freezer/keezer that just has hops and 1 5 gal BB (lagering) so there is quite a bit of airspace. Montanaandy

I took the probe out of the jar for now and also put two cases of bottles in there for good measure (and hopefully to get rid of the rest of my bottled beer). It was still cycling too long and dropping the temp to the high 30's last night with the probe in, so we'll see how it goes...

do you have your anti-short-cycle set too high?

Anti-short cycle prevents it from coming back on too quickly, not forcing it to run for X number of minutes. Right? I initially thought maybe I had that wrong, but I reread the manual and it doesn't seem that I did. I think I put it up to 12 minutes, however.

ah, yeah you're right.

unless you're set up for N.C.

As an appliance repairman, +10 on allowing it to stabilize. When doing a temperature check, I always prefer to take it in liquid.